Apparatus for forming and dewatering webs of fibrous material



w. STOFFEL- June 15, 1965 APPARATUS FOR FORMING AND DEWATERING WEBS 0F FIBROUS MATERIAL I 5 Sheets-Sheet 1 Filed Aug. 2'7, 1962 INVENT OR. WILLY STOFFEL any M44 ATTORNEYS w. STOFFEL 3,189,517

APPARATUS FOR FORMING AND DEWATERING WEBS OF FIBROUS MATERIAL June 15, 1965 3 Sheets-Sheet 2 Filed Aug. 27, 1962 INVENTOR.

WILLY STOFFEL BY CD MW ATTORNEYS w. STOFFEL APPARATUS FOR FORMING AND DEWATERING WEBS 0F FIBROUS MATERIAL 3 Sheets-Sheet 5 Filed Aug; 27, 1962 INVENTOR. WILLY STOFFEL ATTORNEYS United States Patent 4 Claims. cl. 16234S) This invention relates to an apparatus for forming and dewatering webs of fibrous material in the paper-industry, or webs of synthetic plastic material, having an endless I flexible wire cloth which is guided by means of various rollers from a pulp feeding device over tube rolls. and suction boxes to a web-detaching device and back again to the pulp feeding device.

In such apparatus, which are known as Fourdrinier machines, an endless wire cloth made of metal is generally guided about a breast roll arranged at the beginning of the wire part and about a suction roll arranged at the endof the wire part or the lower couch roll of a .couch press, whilst the two runs of the wire cloth situated between the aforesaid rolls are stretched out substantially fiat. The upper, plane run bears substantially on socalled tube rolls and suction boxes and is effectively guided. The lower run, on the other hand, must be guided by rolls of relatively small diameter which are situated alternately above and below it, the. so-called wire guide rolls, which also tension and regulate the wire cloth. The various amounts of deflection occurring as the wire cloth travels about these guide rolls, which cause considerable bending stresses onthe longitudinal wires of the cloth, are primarily responsible for rapid wearing of the cloth. In the case of high-speed Fourdrinier machines, the wire cloth must, therefore, be replaced by a new cloth every few days, and this adds correspondingly to running costs and interrupts the otherwise continuous productionwhich is possible.

Wire cylinder machines are also known wherein th wire cloth bears over its entire length on a rigid circular cylindrical supporting drum provided with liquid apertures, there being no relative movement between the wire cloth and the supporting drum. In these wire cylinder machines, the suction boxes must bear on the inner side of the supporting drum. In this way, however, the removal of the water by suction is less effective owing to the resistance to through flow in the holes or apertures provided for the through passage of the liquid in the supporting drum, resulting in accumulations which may have a disadvantageous efifect on the formation ofthe sheet of material. If the suction boxesd rectly adjoin the wire cloth, such accumulations and therefore their effects are obviated.

The object of the invention is to permit the construction of a machine which does not have the disadvantages of the known Fourdrinier and wire cylinder machines but which combines the advantages of these known machines. In an apparatus of the kind initially specified for forming and dewatering a web of fibrous material, for this purpose according to the invention the suction boxes and the rolls guiding the wire cloth are so arranged and constructed that the wire cloth is disposed substantially in the form of a circular cylinder.

'Ihis provides a machine wherein the web of fibrous material is separated from the dewatering chamber, as in the case of the conventional Fourdrinier machine, merely by the thin, permeable wier cloth and wherein nevertheless this wire cloth is subjected in practice to only very slight bending stresses. The result is the best possible dewatering conditions for the web of fibrous 3,189,517 Patented June 15, 1965 ice material, and .a longer working life for the wire cloth. Furthermore, the machine according to the invention, whilst having a dewatering zone of thesame size, manages with a substantially -shorter. overall length than a Fourdrinier machine, which is a most important feature in view of the size of such machines.

Examples of embodiment of the subject of the present invention are illustrated in a simplified manner in the drawings.

FIGURE 1 is a sectional view through an apparatus at right angles to the axis of the aforesaid circular cylinder.

FIGURE 2 is a sectional view on the line 11-11 of FIGURE 1 on a larger scale.

FIGURE 3 is a sectional view through a further form of embodiment taken on the line IHIII of FIGURE 4, and

FIG. 4 is a sectional view on the line IV1V of FIG- URE 3.

The apparatus shown in FIGURE 1 comprises an endless wire cloth 1 which is guided from a pulp feeding device 3 with adjustable gate 3a, or a plurality of such 'pulp feeding devices, over rolls 2 with adjustable bars 2a intermediate of the said rolls, and over suction boxes 5 to 8 to a web detaching device 9. By Way of a wire cleaning device 10 with spraying nozzles 11 and a trough 12, and by 'way of driving rolls 13 and 14 with counterrolls 15 and 16 the wire cloth returns, supported by further rolls 2, to the pulp feed device 3. In the region of the first dewatering zone, the rolls 2 are provided with a saveall 4 havingan outflow pipe 4a, or a suction box in accordance with the constructions designated by the reference numerals 5 to 8. The rolls 2 are so mounted and the corresponding surfaces of .the suction boxes 5 to 8 are. so constructed that the wire cloth 1 is disposed substantially in the form of a circular cylinder and thus guided along a path of substantially circular configuration. In the region of the pulp feed device 3 and in the immediate vicinity thereof, the wire cloth 1 is expediently disposed ina straight fashion for a short distance. Any desired number of the rolls 2 ,can be constructed as tensioning rolls in which case, as is indicated at one roll, they can be pressed by springs 17 against the wire cloth 1.

The wire cloth 1 is also substantially carried by rolls 2 within the suction boxes 5 and 6, as the detailed view shown in FIGURE 2 illustrates. At the edges, the wire cloth 1 also bears on sealing strips 19 which are arranged in the suction box walls 18, and which, in the example of embodiment, are adapted to be pressed against the wire cloth 1 by a hose 20 into which compressed air can be admitted. Provided between the shaft 21 of the roll 2 and the housing wall 18 is a rubber sealing ring 22. The shaft 21 is mounted by means of ball bearings 23 in a bearing plate 24 fixed to the housing wall 18.

In the apparatus illustrated in FIGURES 3 and 4, the wire cloth 25 departs from the circular cylindrical shape in the region of a driving roll 26, in order to obtain a larger envelope angle for the said driving roll. Also provided are two counter-rolls 2'7 with which the wire cloth 25 is pressed against the driving roll 26. Over the greater part of its path of travel, the wire cloth 25 follows the outline of a circular cylinder. Only in the driving region is it made to deviate from the circular cylindrical form, but even here only to the extent of the radius of the large driving roll 26.

The wire cloth 1 of FIGURE 1 is subjected to substantially no bending stresses worth mentioning during rotational movement, owing to its guidance along a circular cylindrical path of travel. These satisfactory conditions are obtained for by far the greater part of the path of travel of a wire cloth in the case of the cloth 25 shown in FIGURES 3 and 4.

As FIGURE 4 shows more particularly, in the construction according to FIGURES 3 and 4 the parts situated within the Wire cloth 25, namely the suction boxes 7 29. to 34, the save-all 28, the rolls 35 and the driving roll 26 are mounted in a supporting'body fixed-in over,- hung fashion'to: the base 36 and comprising the parts 37- and 38, and the bearing parts for the suction boxes and rolls are situated-inwardly of the cylindrical surface defined by the wire cloth 25. Likewise, the parts .4 situated at the outer side of the wire cloth, narnely the rolls 27,'th e trough 39 for the wire cleaning device and the roll'40 for the web detaching device are mounted on the base 36, and the appropriate bearing parts are situated externally of the cylindrical surface defined by ,the wire cloth -25.

1 In order to interchange the wire cloth, all that has {to -be done, therefore, is to rlift some of the rolls'35 away "from the wire cloth 25 to retain them, in opposition to' the "action of the springs 41 (FIGURE 4),;ai1dthe wire cloth 25 can easily he slid in and out through the gap left free between the parts inside and outside the wire cloth (see arrows 42),- lnsertion can befacilitated-by a device which'carries the wire cloth to be inserted and Y which holds it in the aforesaid cylindricaltsurface.

The 'rol1s35 can all be constructed 'to'be applied by be adaptedlto' be'pressedresiliently on the wire cloth, orthe rolls can be mounted on-fixed axes in'a box which can'be pressed towards the wire cloth. .u v a V The wire drivecan also be'efiected by'a relatively larger number of rrolls guidingtthe-wire cloth] Thedrivwatering zone between the'two; rolls for guiding said wire cloth; and at least one suction box arranged in said dewatering zone; saiddriving means, guide rolls and suction box being arranged to ca'usethewire cloth'to travel along a path free of reverseib'ends and of sub stantially circular configuration at least in theregions of the-pulp feeding device, the dewatering zone and the web detaching device. a 7 7 V 2. An apparatus for forming and dewatering'webs comprising an endless flexible wire cloth,"said' wire cloth forming a loop; a base; a'supp orting'tbo'dy connected in overhung fashion to 'said base; said supportingfbody comprising wire dewatering means with guiding rolls and springs to the wire cloth. Theboxes 29 to 34'canalso ing rolls and also the pairs ofzrolls 13, '154and 14, 16

(FIGURE 1) or theirolls 26,:27 (FIGURE 3), can be provided with an 'elastic covering in order to be careful 3 with the wire'cloth. i 1

Furthermore, some of the wire-supportingtrolls, as is V 7 known in'Fourdrinier machines, can be constructed as regulating rolls. 7 r a i What'is claimed is? a t apparatus for forming and dewatering webs lcomprising an endless flexible wire cloth; driving'means causing-said wire clothto move in its longitudinal direc tiongat least one pulp-feeding device arranged to supply pulp of fibrous material to the outer surface of said wire .cloth so as to form a 'webthereon; a web detaching de-;

vice spaced from said pulp feeding device in the longie at least one suction box arranged internally of said endless wire cloth to support and guide said wire cloth along a path" of substantially circular configuration;- driving meansfcausing said wire cloth to move in itslongitudin'al directionjat least one, pulp feeding device arranged outside saidloop of wire cloth to supply pulp of fibrous material to said'wire 'cloth 'so as t'o'form a web thereon; and a web detaching device mounted externallyof said wire clothya gap beingleft between the partsmounted inside and outside the wire cloth; the gap being left open on one side of the apparatus soas to allow the wire cloth to be removed from the apparatus in a direction transverse to said longitudinal direction; a

3. The apparatusdefined'tin clairn l in which the entire pathrtravelled by thewire cloth is of substantially circular configuration. I t a r V 4. The apparatus defined in 'claim 1 in W hichfthe path travelled .by the wire clothdeviates from ithe substantially circular configuration in the region of thejdriving means; and in which the strands of the wire cloth engagingthe' driving -means are. tangent to the substantially 540,309 6/95 1 1,885,334 11/32 'Darrah'. 7162'295 2,118,491 5/38 Chuse ,162 299 -2,488,700 11/49 ,Bidwell 162- 320 2,943,677 7/60 'Leek' Q. Vl623l0 DONALL H. "SYLVESTER, Primary Examiner, 'MORRIS o. WOLK, Examiner. 1 

1. AN APPARATUS FOR FORMING AND DEWATERING WEBS COMPRISING AN ENDLESS FLEXIBLE WIRE CLOTH; DRIVING MEANS CAUSING SAID WIRE CLOTH TO MOVE IN ITS LONGITUDINAL DIRECTION; AT LEAST ONE PULP FEEDING DEVICE ARRANGED TO SUPPLY PULP OF FIBROUS MATERIAL TO THE OUTER SURFACE OF SAID WIRE CLOTH SO AS TO FORM A WEB THEREON; A WEB DETACHING DEVICE SPACED FROM SAID PULP FEEDING DEVICE IN THE LONGTUDINAL DIRECTION OF THE WIRE CLOTH SO AS TO LEAVE A DEWATERING ZONE BETWEEN THE TWO; ROOLS FOR GUIDING SAID WIRE CLOTH; AND AT LEAST ONE SUCTION BOX ARRANGED IN SAID DEWATERING ZONEF SAID DRIVING MEANS, GUIDE ROLLS AND SUCTION BOX BEING ARRANGED TO CAUSE THE WIRE CLOTH TO TRAVEL ALONG A PATH FREE OF REVERSE BENDS AND OF SUBSTANTIALLY CIRCULAR CONFIGURATION AT LEAST IN THE REGIONS OF THE PULP FEEDING DEVICE, THE DEWATERING ZONE AND THE WEB DETACHING DEVICE. 